Field of the Invention
The present invention relates to a loader attachment system for detachably attaching a loader, e.g., a front end loader, to a vehicle, e.g., a tractor.
Related Art
As disclosed by US 2006/0245899 A1, there is a well-known conventional mechanism configured so that right and left masts of a front end loader is detachably attached to right and left loader mounts previously secured on a tractor so as to detachably attach the front end loader to the tractor. The front end loader includes a pair of right and left arms whose rear ends are pivoted on the respective right and left masts. A working instrument, e.g., a bucket, is attached onto front ends of the arms. An arm cylinder is interposed between each arm and each mast so as to serve as an actuator for rotating the arm relative to the mast.
Each of the masts has an arm cylinder pivot shaft onto which a tip of a piston rod of the arm cylinder is pivoted. A latching arm formed with a hook is also pivotally provided on the arm cylinder pivot shaft. A torsion spring is interposed between the latching arm and the mast. On the other hand, each of the loader mounts includes upper and lower bushed pins. The lower bushed pin serves as a pivot for rotating the mast relative to the loader mount. The upper bushed pin serves as a latched pin onto which the hook of the latching arm is hooked to lock the mast to the loader mount.
To attach the masts of the front end loader (with the bucket) to the loader mounts of the tractor, the front end loader is previously set so that the bucket, mounted on the front end of the front end loader, and a parking stand, extended forward and downward from the masts, are placed on the ground. Then, the tractor approaches the placed front end loader and stops. Hydraulic pipes are provided to fluidly connect the hydraulic actuators of the front end loader to the tractor. An operator seated on the tractor operates to contract piston rods of the arm cylinders so that the lower bushed pins of the loader mounts are received by respective receptacles formed on bottom edges of the right and left masts. Once the lower bushed pins are fitted in the receptacles, the piston rods of the arm cylinders are further contracted to rotate the masts centered on axes of the lower bushed pins relative to the loader mounts so as to lift the parking stand upward apart from the ground. Also, the contraction of the piston rods of the arm cylinders cause overcenter action of the torsion springs and location of the latching arms at their latching positions. Therefore, finally, the latching arms are biased by the torsion springs so as to be hooked on the upper bushed pins of the loader mounts, thereby completing the attachment of the masts of the front end loader to the loader mounts of the tractor.
To detach the masts of the front end loader from the loader mounts, first, the seated operator operates the front end loader to place the bucket on the ground, and the operator operates toe pad portions of the latching arms with his/her foot so as to forcedly disengage the latching arms from the upper bushed pins. In this regard, due to the force of the operator's foot, at first, the latching arm rotates around the axis of the arm cylinder pivot shaft against the force of the torsion spring biasing the latching arm to the latching position. However, once the overcenter action of the spring occurs, the spring comes to bias the latching arm to its unlatching position, where the latching arm abuts against a part of the piston rod of the arm cylinder, thereby easily completing the disengagement of the masts from the loader mounts. Then, the seated operator operates to extend the piston rods of the arm cylinders to rotate the masts relative to the loader mounts so that the receptacles of the masts can easily be separated from the lower bushed pins of the loader mounts.
In this way, the latching of the masts to the loader mounts via the latching arms relies on the telescopic operation of the piston rods of arm cylinders. In other words, the upper bushed pin of each loader mount defines both the latching position of the latching arm and the attachment position of the mast relative to the loader mount. Moreover, both the location of the masts relative to the loader mounts and the latching of the masts to the loader mounts depend on the rotation of the masts relative to the loader mounts centered on the lower bushed pins. Such a structure seems to require a great accuracy in dimensioning of the latching arms in shape and location relative to both the upper and lower bushed pins so as to increase manufacturing costs.
Further, to detach the masts from the loader mounts, an operator, who may sit on the seat or stand on a platform in front of the seat, has to use his/her foot to operate the toe pad portion formed on the rear end portion of each latching arm so as to detach the latching arm from the upper bushed pin. This operation using the operator's foot seems to be laborious. Moreover, this unlocking manner is not adaptable to a cabin tractor because an operator inside of a cabin cannot access a front end loader outside of the cabin. In other words, each latching arm of the front end loader is formed with the toe pad portion suitable for operation by an operator sitting on the seat or standing on the platform, so that it seems to be hard for a person, who stands beside the tractor (i.e., does not ride the tractor), to access and operate the latching arm for unlatching the latching arm from the upper bushed pin. Therefore, to provide a loader attachment system adaptable to a cabin tractor, the loader attachment system should have a structure enabling an operator outside of a cabin to operate for unlocking masts from loader mounts.